1. Field of the Invention
The present invention generally relates to systems for continuiously monitoring the pressure of air in inflatable tires of vehicles and aircraft, and more particularly concerns tire air pressure systems that may be installed during the manufacture of the vehicle or aircraft or added as an after-market accessory, and are capable of safely, continuiously, and accurately monitoring the pressure of air in inflatable tires and activating an audio and/or visual warning when the pressure in a tire falls below a predetermined level.
2. Description of the Prior Art
The array of systems that may be used to continuiously monitor the air pressure of inflatable tires of vehicles and aircraft includes those systems utilizing an electromechanical sensor, valve or similar disposed near a tire acting in response to a decrease in the air pressure of a tire. The electromechanical sensors and valves are frequently maintained at positive electrical potential, and act to close electrical contacts, completing an electrical circuit and thereby activating an audio and/or visual alarm. In this way, the operator of the vehicle or aircraft may be alerted to an impending dangerous condition. Such systems may utilize slip rings and brush contacts to provide electrical connection between a rotating tire and wheel and the vehicle or aircraft upon which the tire and wheel are mounted. A variety of electromechanical sensors and valves are used by such systems, including those systems where changes in air pressure causes movement of a flexible diaphram, such as those described by U.S. Pat. Nos. 1,140,937, 2,445,664, and 2,846,664, a bellows, such as those described by U.S. Pat. Nos. 1,975,639 and 3,537,068, a metal disk, such as that described by U.S. Pat. No. 1,167,980, or a piston, such as that described by U.S. Pat. No. 3,757,294.
Unfortunately, such existing systems may be difficult or impossible to incorporate for use with a vehicle or aircraft as an after-market accessory, or may require extensive, time consuming and costly modification of wheels, axles or other components. In addition, thoses systems utilizing diaphrams or bellows may be subject to rapid wear, fatigue, or failure, especially in extreme weather environments. Moreover, in those systems where components proximate to wheels are maintained at a positive electrical potential, the danger of electrical shocks and failures is present.
Despite the availability of such systems, there exists a need in the art for a tire air pressure system that is capable of reliably and continuiously monitoring the pressure of air in an inflatable tire while minimizing the danger of electrical shock, yet may be easily installed as an after-market accessory.